Beamed emission from a neutron-star ULX in a GRRMHD simulation

Understand

We perform a global 2.5D general-relativistic radiation magnetohydrodynamic simulation of super-critical accretion onto a neutron star with a $2\times 10^{10}$ G dipolar magnetic field, as a model of a neutron-star-powered ultraluminous X-ray source (ULX).

• We compute a lower limit on the total luminosity of $\sim 2.5\,L_\mathrm{Edd}$, and find the radiation to be highly beamed by the accretion disk outflows.
• The apparent isotropic luminosity, which is a function of the viewing angle, reaches a maximum above $100\,L_\mathrm{Edd}$, consistent with the luminosities observed in ULXs.